Only a few of the gamma records require additional individual interpretation. The Wahoo record from Coracle CR 4.1 (Figures 3.77 and 3.164) may be useful for determining the decay rate of water directly contaminated by the detonation. This coracle overturned at an estimated time of 1.1 minutes and remained at its moored position until approximately 8 hours after zero time. White water reached the coracie at approximately 6 minutes and remained in the vicinity for about an hour. When recovered, the instrument well of this coracle contained about an inch of radioactive water (approximately 180 liters, reading 160 mr ‘hr at 75.6 hours), which presumably represents a sample of white water taken sometime within the first hour after the detonation. The 0- to 6-hour record for CR 4.1 (Figure 3.164) is a smoothly decreasing decay curve from about 30 minutes to the end of the record. Since the std-GITR dome is sealed directly to the instrument weil cover, this record is then a decay curve for white water obtained through approximately '4 inch of aluminum. The gamma record from Coracle CL 6.0 for Umbrella (Figure 3.84) represents a distant transit, but the observed dose rate is complex, showing a second rise in dose rate higher than the first, an occurrence which at first appears contradictory. A number of similar occurrences are revealed when the normalized rate curves for other distant or edge transits are inspected, viz, CL 4.6 for Wahoo and CR 4.9 for Umbrella (Figures 3.68 and 3.96, respectively). Such records are probably caused by a temporary decrease in surface wind speed at a time when the base surge is still actively expanding. All free-field gamma dose rate records, together with their respective boundary plots, transit plots, and addittonal tabular data, are presented on the pages that follow. Coding must be used in order to condense a maximum amount of information into a minimum space. The coded designators have been Selected so that, with some familiarity, their meanings should be immediately apparent. Many of the terms or coded designators have already been explained in the text of this section; however, all designators and special conditions of tabulation are fully described in the keys preceding the free-field records themselves or at the front of Appendix F. 3.3.3 Free-Field Isodose Contours. The principal sources of contour data are: (1) cumu- lative doses at various times after zero time from the std-GITR for the early time contours, augmented in the final contours by (2) film pack information. The GITR cumulative doses are presented in Table 3.9 and all film pack information is summarized in Table 3.12. Oblique photography of the base surge taken by aircraft circling the event at an altitude of 10,000 feet and a slant range of approximately 23,000 feet was used to check contour shapes against base surge positions at early time, (the estimated accuracy of these surge boundaries is presented in Section 3.3.2). The total cumulative dose recorded by a std-GITR and the total dose registered by a NBS film pack installed at the same location show good correspondence (Figure 3.97). Similar correlation has been previously reported for similar combinations of film packs and recording ion chambers (References 33 and 132). Both the directional and energy response of the NBS film packs are considered compatible with the std-GITR (Section C.4). Thus, the film pack dose may be converted to an equivalent total GITR dose by the factor of 1.25, the slope of the straight line through the data plotted in Figure 3.97. Tripod film packs (Section 2.2.5) are considered directly comparable with the std-GITR when the coracle did not overturn, whereas FFP’s are converted to an equivalent std-GITR dose by comparing them with the float packs attached to nearby coracles. The variation between the three types of film packs is usually small, being caused primarily by differences in the total solid angle of the radiating cloud subtended and by the effects of radioactive water. The few large discrepancies between a tripod and an FFP dose may be explained by overturn and subsequent passage of radioactive foam (Section 3.3.5). The contours presented in this section are constructed by means of the logarithmic method described in References 95 and 96. All cumulative dose information is first converted to an equivaient std-GITR dose for a given station. These data points are mapped and then connected by straight lines along which the difference in dose between the two positions is marked off ac- (Text continued on Page 204) Pages 140 through 203 deleted. Xo 139